94SRUNNER
GOLD Star
Sound advice as usualCorrect! Just as I've post many of times. It works, and is only sure method!
Provided no air bubble blockage. Which I've only seen bubble blockage in heater core(s). Which you can easily tell as Water temp gauge reads normal (3 o'clock), but cabin heater does not blow very hot as it should. I hit the brakes hard at ~30 MPH and I hear gurgling sound as bubble dislodged, than heater blows hot. May need to top rad again.. This only happens sometime, when I blow out heater cores. But low coolant will not reach heater cores at all, or until very hot (expansion). This too result in no or low cabin heat.
I can't say you don't have other issue that may needing attention. But over night cool down, is best way to top and remove air in a properly serviced coolant system.
What happens is, by parking front end high. The radiator top become high point. Air bubble will form at high point as coolant cools and contracts. But if you open the cap before full cool down, you loose vacuum of contraction. The contraction vacuum sucks coolant from reservoir. But fail to do so efficiently if air bubble at top of radiator (goose neck of cap). Fails if reservoir hose clogged. Fails if reservoir hose end is not submerged in coolant (sucks air)
A stuck closed thermostat, will result in overheating.
A weak thermostat will result in not reaching operating temp.
A very low coolant system will result in overheating and blowing engine.
Weak cap will result in runn cool.
Stuck cap will result in over pressurizing and likely overheating.
Clogged radiator fins (washe the fins( result in running hot even overheating.
Radiator fins need cleaning! Alert Alert Alert
I've a 06LC w/192K I just bought. In reading history I found PO complained of engine temp raising when both front and rear AC on. Toyota Dealership diagnosed with clogged radiator fins. Recommended new OEM radiator, $600 for the US spec Radaitor plus coolant and labor. They should have added...forum.ih8mud.com